Analysis On Surrounding Rock Of Yaojiashan Double-track Tunnel

With the rapid development of the state high grade construction, there are more and more highway tunnels, especially long highway tunnels. In the course of the highway tunnel's construction, the stress in rock mass will redistribute around grotto, when this kind stress exceeds surrounding rock's ultimate strength, surrounding rock will lose its stability and destruct. Consequently, it becomes increasingly important for the study of the stability of surrounding rock and its forced condition of the structure during construction of highway tunnels.Associated with the project of Yaojiashan tunnels, which is part of the Lianyugang to Huoerguosi highway in Shannxi, sticking to the evaluation of surrounding rock's stability and direct highway tunnel's construction, with the combination of qualitative evaluation, quantitative evaluation, integrate and local evaluation, the surrounding rock's stability of tunnels is studied systematically.Starting with the engineering geological factors influencing surrounding rock's stability of tunnel, the paper carries on the analysis and discussion about deformation and destruction mechanism to surrouding rock. According to structural surface development and elastic-plastic geological characteristics, intensity-tress control type is put forward. And the top arch is the weak point; According to the specific engineering geological conditions of Yaojiashan double-track tunnel, the HC method, the RMR method and the Q method are used. Then the surrounding rock of Yaojiashan double-track tunnel is classified qualitatively and quantitatively. Finally ,the classification is divided into three types:â…¢surrounding rock,â…£surrounding rock andâ…¤surrounding rock; Based on the analysis of the basic theory about the interaction mechanism of the surrounding rock and support structure in construction, a spatial computation model is a numerical computation method with 2-D elastic-plastic finite element is proposed to analyze stability and safety of theâ…¢surrounding rock in construction, through analyzing the distributing law of displacement, stress and strain in rock mass followed with tunnel's construction, some beneficial conclusions are gotten, which is of guiding meaning for evaluation of stability and security in surrounding rock during construction of long highway tunnels.